The present invention relates to a flat end head of a flat rod for a revolving flat of a card.
In cards of the respective category a multiplicity of flat rods are led on a sliding guide over the card drum. This arrangement is also called revolving flats. They are connected by an endless component, for example a belt or a chain, and are moved by a drive means. Both the flat rods and the cylinder have a clothing with clothing points, for example, fine needles or in the form of a saw tooth. The clothing on both the flat rods and the cylinder reciprocally work with one another for the cleaning and the aligning of the fibers. In order to achieve a carding result, it is particularly important that the distances between the flat rods and the card cylinder, and/or the distance of the clothing points, are maintained accurately. The carding gap between the two clothings is a few tenths of a millimeter at the most.
The flat rods comprise a flat end head each at their ends. The flat end head has a mounting section for the mounting with the end of the flat rod and at least one sliding surface. Usually the flat end head furthermore has a device, for example, a recess, in order to attach the endless component. An example of such a combination, consisting of the flat rod, an endless component, and the flat end head is disclosed in the patent specification EP 0 627 507 B1.
The sliding surfaces of the flat end heads are at the same time the surfaces with which the entire flat rod rests on the sliding guides. They have furthermore the function of cooperating with the sliding guide, and providing a low friction and dimensionally accurate running of the flat rod. It is, therefore, important that the flat end head and the sliding guide are co-ordinated accurately with each other, so that the distance between the flat rod and the cylinder (between their respective clothing points) can be held within a predetermined range of tolerance.
Due to the sliding movement of the flat end head on the sliding guide, the sliding guide and/or the sliding surface of the flat end head are subjected to wear. The wear of the sliding guide or the sliding surface of the flat end heads is essentially a question of the applied material combination. The wear can also be reduced and/or minimized by the application of lubrication devices (e.g. oil lubrication).
The sliding guide on the card is traditionally made of cast iron. The latest state of the art, for example according to EP 620 296 or EP 361 219, discloses sliding guides with sliding strips made of polymer material. The latter disclosure does not disclose which type of material is being used for the flat end head. EP 620 296 discloses cast iron or stable metal for the flat end heads. Beside these materials, furthermore, solid steel (U.S. Pat. No. 4,827,573) or aluminium/aluminium alloy (U.S. Pat. No. 4,300,266) are specified for the manufacturing of the flat end heads. In these patent specifications, however, no specifications are given concerning the material for the sliding guide.
In order to increase the gliding ability of these flat end heads, according to the state of the art, guiding shoes are also being provided which are attached to the flat end head. Patent specification U.S. Pat. No. 4,300,266, for example, shows a flat shoe which, if necessary, is interchangeable. However, this flat shoe is pushed onto the flat head by shifting it in an axial direction and by attaching it by means of clips. A disadvantage of this solution is the extraordinary effort required during replacement of the flat shoes. The play in the direction perpendicular to the longitudinal axis of the flat rod, which is necessary for sliding the flat shoe onto the flat rod, is disadvantageous for the accurate allocation of the flat rod with respect to the cylinder.
Other examples of guiding shoes are disclosed in the U.S. Pat. No. 4,300,266, wherein as material for the guiding shoe phosphorus/bronze or a polymer material, for example MoS2/Nylon or a combination containing PTFE, are being suggested. DE 198 34 893 discloses a polymer material guiding shoe, for example, made of polyamide material.
In practice guiding shoes are also glued. Not only are the additional expenditures to replace the old guiding shoe and to remove the adhesive material disadvantageous, but also, when adhering the new shoe, the adhesive material can smear, which can substantially impair the flat rod in its function. Only a very precise job can prevent these irregularities, this precision requires, however, a substantial additional extra effort.
In summary, for the present flat-rods, flat-end-heads are applied which are made of steel or cast iron and which are partially provided with guiding shoes. Although this combination is sufficient for the requirements of the flat rods, it is still disadvantageous for the manufacturing. Depending on the type of frame, approximately 100 flat rods are used on a machine. Each additional component on a complete flat rod increases the production costs.